1984 Oldsmobile Cutlass chargeing

Hi my car wont charge I have ceck all + and - conection and all are good and ive check volts on the batt and the alt and they are good but I always have to jump my car off it has a 307 crate motor and a heavy duty atl on it for the radio my friend tells me that one of the wires that plug into the top might be bad some where the motor it had in it was the 4.3 v6 I dont know what to think it has been a on going problem for a while now and I cant find any wireing diagrams any where can you help thanks chad